The present invention relates to use of soluble CD27 as a biomarker to predict the reponse to an immune checkpoint inhibitor treatment. Inventors have worked with two cohorts of patients and have identified a soluble marker, CD27, present in the plasma of patients with renal cell cancer whose pre-treatment concentrations predict the response to anti-PD-1 / PD-L1. This marker appears more as a predictive marker of response to anti-PD1 / PD-L1 treatment, than as a prognostic marker. Indeed, it is not associated with better survival in patients with metastatic renal cell cancer treated with an antiangiogenic agent. This marker is not correlated with conventional clinical markers of severity that classify patients with metastatic renal cancer.